1. Field of the Invention
This invention relates generally to an apparatus for opening and closing connections among passages that carry air in a heating, ventilation and air conditioning (HVAC) plenum.
2. Description of the Prior Art
A plenum assembly for carrying air in a supply system includes a duct with an inner surface through which air can flow and a door supported for movement between a multitude of open positions, at which flow through the opening is relatively unobstructed, and a sealed position, at which flow through the opening is relatively obstructed. Some positions of the door produce a small gap between the seal and the inner duct surface. The present invention includes a modification to the seal in which this gap has a continuously variable width along at least a portion of a length of the seal.
The variable edge profile provides a gap having a variable width and prevents uniform airflow over the seal. As a result, objectionable high frequency tones and whistles are prevented without compromising the functionality of the seal.
A need exists in the industry for a technique that prevents objectionable noise when the door moves near the sealed position.